holds as is the case for wide-angle Compton scattering [1]}, [2]}. Thus, the experimental
observation of an approximate mirror symmetry between \(A_{LL}^P\)  and \(K_{LL}^P\)  signals the dominance
of twist-3 contributions to pion photoproduction. With regard on that feature \(A^P_{LL}\)  and \(K^P_{LL}\) 
play a similar important role for the discrimination between twist 2 and twist 3 in photoproduction of pions as
the longitudinal and transverse cross sections in DVMP.
In Fig. REF  we show the helicity correlations for \(\pi ^\pm \)  photoproduction at \(s=10.3\,\,{\rm GeV}^2\) .
They are very similar for these cases.
In the backward hemisphere \(A^P_{LL}\)  and \(K^P_{LL}\)  are mirror symmetric which reflects
the twist-3 dominance there. On the other hand, in the forward hemisphere where the twist-2 contribution becomes
increasingly more significant \(A_{LL}\)  and \(K_{LL}\)  approach each other. The energy dependence of the helicity
correlation parameters is very weak.
\(\pi ^0\)  photoproduction has been discussed by us in [3]} in great detail. The helicity correlations
for this channel reveal the approximate mirror symmetry in the forward hemisphere too since the twist-2 contribution
is also tiny in that region, see Fig. REF .
<FIGURE>